This invention relates to a device for promoting health and rehabilitation through exercise by way of providing motion to one's legs. More particularly, the present invention relates to such a device which gives a rotary motion to the legs of a user, while those legs are in a passive state, while that person is in a wheelchair or seated position away from the device.
Rotary, health promoting, powered exercise machines have long been known for providing helpful exercise and therapeutic treatment for children and adults who have different degrees of disabilities. Individuals who have suffered partial paralysis, e.g. spinal injury, strokes, arthritis, chronic back pain, multiple sclerosis, muscular dystrophy and the like have the need to exercise or range their unused or underused muscles or limbs. Failure to do so can result in stiffened joints and tendons, and atrophy of the muscles leading to a generalized limb pain as well as a general deterioration of the cardiovascular system including increased susceptibility to blood clots. On the other hand, the therapeutical value of even strictly passive limb exercise is quite indisputable for helping to counteract the effects of long term immobilization. Such exercise tends to make joints more flexible, helps prevent atrophy of muscles and tendons, increases circulation thus removing the causes of pain in a limb, enables the heart to work more efficiently, and gives rise to a general feeling of well being.
Patents of general background interest relating to leg exercise devices for persons in wheelchairs include Canadian Patent No. 891,657 of McGuire issued Jan. 25, 1972, Canadian Patent No. 1,177,503 of Peters issued Nov. 6, 1984, Canadian Patent No. 1,202,221 of Schotten issued Mar. 25, 1986, Canadian Patent No. 1,255,709 of Kopnicky issued Jun. 13, 1989, U.S. Pat. No. 4,615,335 of Searcy issued Oct. 7, 1986, U.S. Pat. No. 4,717,146 of Nohara issued Jan. 5, 1988, U.S. Pat. No. 4,773,399 of Richardson issued Sept. 27, 1988 and U.S. Pat. No. 4,869,494 of Lambert issued Sept. 26, 1989.
Other patents of general background interest relating to exercisers for disabled persons, on which the disabled persons are seated, include Canadian Patent No. 1,140,181 of Reynolds issued Jan. 25, 1983 and U.S. Pat. No. 4,863,157 of Mendel, et al issued Sept. 5, 1989.
Such known devices have been subject to a number of disadvantages. While all have some sort of a rotating pedal mechanism on which the user's leg is positioned during operation, most have provided a fixed amplitude for the crank arm which orbits the leg on the pedals. This means that unless the amplitude chosen is very small, the device cannot be used by children or adults with a small range of non-painful movement such as would occur after an accident or operation or after a long period of inactivity. In such cases, it is desirable to start off with a small range of movement and work up to larger amplitudes of orbital motion as flexibility in the joints, muscles and tendons is restored.
Another limitation of such known devices concerns the restraint system used to guide paralysed limbs during their orbital motion. In this regard, it should be understood that the upper end of the leg is anchored firmly into the hip joint which leaves the knee and ankle free to pivot about an axis perpendicular to the plane of orbital motion of the pedals. However, in a paralysed limb, as the knee bends, there is a tendency for the knee to flop either inwards or towards the other knee, or outwards to the point where severe damage to joints and tendons can occur. Various techniques have been used to overcome this problem. In general, the foot is secured to a foot holder on the pedal having restraining straps and two or more raised edges, the foot holder in turn being attached to a pedal. Peters Canadian Patent No. 1,177,503 teaches an L-shaped attachment to the pedal which secures the lower leg at right angles to the foot. While very effective in preventing unwanted lateral movement of the knee, the disadvantage of this method is that the beneficial effects of movement on the ankle and achilles tendon are prevented. For a stroke victim, exercise of the ankle and achilles tendon is necessary to retain the ability to put the heel on the ground when standing.
Another method of restraint that has been previously used has been to insert some part of the apparatus between the legs so that inward movement of the legs is prevented by contact with smooth panels (see e.g. Peters Canadian Patent No. 1,177,503 or Schotten Canadian Patent No. 1,202,221). This however gives rise to rubbing on the inside of the knee and does not prevent the knees from flopping outwardly during operation of the devices in question, although it does enable the ankles to move normally.
A further disadvantage of such known devices for movement of passive legs is that they invariably confine themselves to a mode of operation where the axis of rotation of the foot pedal is always parallel to the axis of rotation of the crank. This restricts the range of motion available for a limb such as a leg, which has a reasonable degree of flexibility.
Maxwell U.S. Pat. No. 4,973,046 issued Nov. 27, 1990 describes and illustrates an adjustable therapeutic exerciser for lower human extremities comprising a pair of motor driven pedal cranks carrying pedals on the outer arms. The pedals extend laterally outwardly parallel to the axis of rotation of the cranks, and have pedal plates which are universally adjustable by way of a ball and socket arrangement, over each of the pedals. In this manner the foot supporting plates may be adjusted for comfort of the user and to provide a different, albeit constant, angular adjustment of each foot plate throughout each rotation of the crank arm, depending on the selected angular positioning the plate.
Redding U.S. Pat. No. 4,478,213 issued Oct. 23, 1984 describes and illustrates a therapeutic manipulator wherein, motor driven pedals are provided. The device further has a pair of knee support straps supported for lateral movement in a hollow support arm. For the knee support straps to operate properly, both legs must be supported, so that one end of the strap is counter-balanced by the other during operation of the device.
It is an object of the present invention to provide a device for exercise of passive legs by a patient seated in a wheelchair or the like, which overcomes the above-noted problems.
It is a further object of the present invention to provide a passive leg exerciser which will provide a wobble-like motion to the legs, during operation, to further enhance joint and muscle mobility in the user's legs.